聚乙二醇/石墨烯复合相变储能材料界面结构调控和构效关系研究

Energy storage technologies using phase change materials (PCMs) are the simplest, least expensive and most efficient way to store thermal energy and open an avenue minimizing energy consumption and popularizing the use of renewable energy. Among the shortcomings of PCMs, their low thermal conductivity, low latent heat storage capacity and variation in thermo-physical properties under extended cycles have been major concerns in view of the widely adopted and stringent requirement to store/release (charge/discharge) thermal energy over a desired time period. We will develop a high thermal conductive, high latent heat storage and high thermally stable polyethylene glycol (PEG)/graphene PCMs. The thermal properties of the PCMs will be correlated with the interfacial structures of the PEG/graphene composites through surface structure design of graphene. The causal relation between the thermal conduction mechanisms and phase transition behaviors of the composites and the interfacial structures is expected to be found. The thermal conductivity, latent heat and cycling stability of the composites could be simultaneously improved. The problem of decline in latent heat storage capacity caused by introduction of conductive fillers can reasonably be expected to be solved. This project will deliver the mechanism and method to manipulate the interfacial structures and thermal properties to prepare high-performance PEG/graphene composite PCMs with a simple, efficient and eco-friendly fabrication process.

相变储能技术是目前最简单、廉价和高效的热能存储策略，为大规模降低能源消耗和可再生能源的普及提供了一条有效途径。目前的相变材料存在热导率和潜热低、循环稳定性差等主要问题，仅通过使用高导热填料和改善复合相变材料界面相容性并不能有效解决上述问题，复合相变材料结构与热性能之间的构效关系尚未探明。本项目将开发一种具备高热导率、高潜热、高热稳定性等特点的聚乙二醇/石墨烯复合相变材料。通过对石墨烯进行表面结构功能化设计，调控复合材料界面结构，探明界面结构同导热机制和相变行为之间的关键联系，建立聚乙二醇/石墨烯复合体系的界面结构与热性能之间的调控机制。通过优化复合材料界面结构控制导热机制和相变过程，突破复合相变材料因导热材料填充而引起的潜热下降问题，同步提高材料导热和储热性能，为相变储能材料的规模化应用建立一种简单、高效和环境友好的策略。

当前相变材料领域面临的主要问题包括材料热导率和潜热低、循环稳定性差等主要问题，仅通过使用高导热填料和改善复合相变材料界面相容性并不能有效解决上述问题，复合相变材料结构与热性能之间的构效关系尚不明确。本项目通过在氧化石墨烯（GO）表面接枝聚乙二醇（PEG）制备了PEG-g-GO，将其引入到PEG/GO共混体系中，深入研究了PEG-g-GO对PEG/GO复合体系界面结构和相互作用的影响，并通过相变行为和导热性研究，揭示了PEG/PEG-g-GO/GO复合材料相变焓和热导率同步提高的关键机理。在此基础上利用PEG的相变行为，将PEG/GO与聚偏二氟乙烯（PVDF）溶液共混及热压制备了具有可调介电性能的复合介电开关材料，揭示了PVDF/PEG/GO复合材料的介电性能与PEG相变行为和复合材料结构之间的联系，并以此建立了基于有机相变的介电开关性能调控机制。本项目将为新型高性能相变材料和新型介电开关材料的结构设计、制备和应用提供科学理论和实用技术。